Rocks and Rock Formation Rocks are pieces of Earth’s crust! Bedrock is the actual rock that makes up Earth’s crust. See picture… These bedrock layers have been exposed by erosion! Each layer is a different type

Rocks and Rock Formation Smaller rocks are pieces of bedrock that have broken off. These are called sediments. These are boulders… These are pebbles and cobbles

Rocks and Rock Formation There are several types of sediments. See ESRT p.7 Larger than 0.2 cm Sand is .006cm - .2cm Silt is .0004cm - .006cm Clay is < .0004cm

Rocks and Rock Formation Rocks made from sediments are called… Sedimentary Rocks Made from round pebbles Made from angular pebbles Made from sand Made from silt Made from clay Sedimentary rocks made from pieces of other rocks are called… CLASTIC!

Rock Formation: Clastic Sedimentary Rocks How do CLASTIC sedimentary rocks form? Compaction and cementation of land derived sediments Sediments are transported- moved by the stream! Sediments are deposited- dropped at stream mouth Sediments pile up in layers! Clastic rock forms by compaction and cementation of sediments STREAM flowing to OCEAN

Rock Formation: Sedimentary Rocks Organic (living) sediments form BIOCLASTIC rocks... Small shell fish and other organisms die and and are deposited at the sea floor Organic sediments are deposited, compacted and cemented… Form limestone and other organic rocks

Rocks and Rock Formation Sedimentary rocks forming from fragments of organisms are called… Bioclastic! Shells or plant remains

Evaporation from water forms Rock Formation: Sedimentary Rocks Evaporation from water forms CHEMICAL EVAPORITES… There are always sediments dissolved in water Water evaporates and sediments get left behind! Rock salt is formed this way! Rock Salt left from evaporation

Precipitation from water forms CHEMICAL PRECIPITATES Rock Formation: Sedimentary Rocks Precipitation from water forms CHEMICAL PRECIPITATES Sediments form from a chemical reaction and are deposited… Rock gypsum, dolostone and limestone form this way! Rock Gypsum left from precipitation

Rocks and Rock Formation Sedimentary rocks forming from evaporation or precipitation are chemical sed. Rocks! Precipitates & Evaporates

Rock Formation: Sedimentary Rocks Evidence of how sedimentary rocks form… Ripple marks from water movement preserved in rock Sandstone Shell fossils from dead animals preserved in rock! Limestone Fossils ONLY form in sedimentary rock!!

Summary Questions… 1. Type of rock formed by compaction and cementation of sediments at the bottom of the ocean… 2. Rock gypsum left behind after precipitation of minerals is what type of rock… 3. Dolostone can be left behind after ocean water has evaporated . What type of rock is it? 4. Plant remains are compacted to form coal, which is what type of rock? 5. Clastic sedimentary rock made from compaction and _________ of sand is called ___________

Rock Formation: Sedimentary Rocks Land-derived sediments form CLASTIC rocks Large pebbles settle first! Tiny clay sediments settle last! Shale forms from clay at the top! SHALE Sandstone and siltstone form Sand , then silt settle Conglomerate forms from pebbles at the bottom Sediments Settling in OCEAN

Rock Formation: Metamorphic Rock How do REGIONAL metamorphic rocks form? Existing rock is buried under heat and pressure Existing rock buried deep! Heat and pressure change the rocks… …Crystals grow, rocks get harder and more dense …Foliation and banding can occur too!

Rock Formation: Metamorphic Rock How do CONTACT metamorphic rocks form? Existing rock is heated by contact with magma ..Existing rock changes when it is heated Crystals grow, rocks get harder and more dense

Summary Questions… ____ metamorphic rocks form when exiting rocks are buried deep below the surface. Foliation and banding usually happen with what type of metamorphism? Non-foliated rocks tend to form with what type of metamorphism? Sandstone is metamorphosed to form a non-foliated metamorphic rock called _____. What type of metamorphism is this?

Each rock can change into any other rock! Rock Cycle Animation Each rock can change into any other rock! Igneous rock can be broken into sediments… …compacted and cemented to become… SEDIMENTARY ROCK

Each rock can change into any other rock! Rock Cycle Animation Each rock can change into any other rock! Igneous rock can be put under heat and pressure… …metamorphosed and turned into… METAMORPHIC ROCK

Each rock can change into any other rock! Rock Cycle Animation Each rock can change into any other rock! Igneous rock can be buried and melted… …turned into magma… …and solidified back into… IGNEOUS ROCK

Summary Questions… What has to happen to a sedimentary rock to turn into an igneous rock? What has to happen to a sedimentary rock to turn into an metamorphic rock? What has to happen to a metamorphic rock to turn into an igneous rock? What has to happen to a metamorphic rock to turn into an sedimentary rock?